On Wed, 11 Jun 2025 at 15:38, Thomas Weißschuh <thomas.weisssc...@linutronix.de> wrote: > > UAPI selftests may expect a "normal" userspace environment. > For example the normal kernel API pseudo-filesystems should be mounted. > This could be done from kernel code but it is non-idiomatic. > > Add a preinit userspace executable which performs these setup steps > before running the final test executable. > This preinit executable is only ever run from the kernel. > Give it access to autoconf.h and kconfig.h to adapt itself to the > tested kernel. > > Signed-off-by: Thomas Weißschuh <thomas.weisssc...@linutronix.de> > ---
Looks good and works here.
Reviewed-by: David Gow <david...@google.com>
(Although, personally, _I wish_ it were more idiomatic to mount things
from kernelspace.)
Cheers,
-- David
> lib/kunit/Makefile | 9 ++++++-
> lib/kunit/uapi-preinit.c | 63
> ++++++++++++++++++++++++++++++++++++++++++++++++
> lib/kunit/uapi.c | 11 +++++++--
> 3 files changed, 80 insertions(+), 3 deletions(-)
>
> diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile
> index
> e406a31df1df834a87961663de0b7921b59481c2..19493ec320c61e2ccbb58e8b2e943e9a4ec447e2
> 100644
> --- a/lib/kunit/Makefile
> +++ b/lib/kunit/Makefile
> @@ -12,7 +12,14 @@ kunit-objs += test.o \
> device.o \
> platform.o
>
> -kunit-$(CONFIG_KUNIT_UAPI) += uapi.o
> +userprogs += uapi-preinit
> +uapi-preinit-nolibc := $(CONFIG_ARCH_HAS_NOLIBC)
> +uapi-preinit-userccflags += -static \
> + -include include/generated/autoconf.h
> \
> + -include
> $(srctree)/tools/include/linux/kconfig.h
> +blobs += uapi-preinit.blob.o
> +uapi-preinit.blob-symbol := kunit_uapi_preinit
> +kunit-$(CONFIG_KUNIT_UAPI) += uapi.o uapi-preinit.blob.o
>
> ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
> kunit-objs += debugfs.o
> diff --git a/lib/kunit/uapi-preinit.c b/lib/kunit/uapi-preinit.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..81182039965a8c93aebb2d5d76f4113bfef277a6
> --- /dev/null
> +++ b/lib/kunit/uapi-preinit.c
> @@ -0,0 +1,63 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KUnit Userspace environment setup.
> + *
> + * Copyright (C) 2025, Linutronix GmbH.
> + * Author: Thomas Weißschuh <thomas.weisssc...@linutronix.de>
> + *
> + * This is *userspace* code.
> + */
> +
> +#include <sys/mount.h>
> +#include <sys/stat.h>
> +
> +#include "../../tools/testing/selftests/kselftest.h"
> +
> +static int setup_api_mount(const char *target, const char *fstype)
> +{
> + int ret;
> +
> + ret = mkdir(target, 0755);
> + if (ret && errno != EEXIST)
> + return -errno;
> +
> + ret = mount("none", target, fstype, 0, NULL);
> + if (ret && errno != EBUSY)
> + return -errno;
> +
> + return 0;
> +}
> +
> +static void exit_failure(const char *stage, int err)
> +{
> + /* If preinit fails synthesize a failed test report. */
> + ksft_print_header();
> + ksft_set_plan(1);
> + ksft_test_result_fail("Failed during test setup: %s: %s\n", stage,
> strerror(-err));
> + ksft_finished();
> +}
> +
> +int main(int argc, char **argv, char **envp)
> +{
> + int ret;
> +
> + ret = setup_api_mount("/proc", "proc");
> + if (ret)
> + exit_failure("mount /proc", ret);
> +
> + ret = setup_api_mount("/sys", "sysfs");
> + if (ret)
> + exit_failure("mount /sys", ret);
> +
> + if (IS_ENABLED(CONFIG_DEVTMPFS)) {
> + ret = setup_api_mount("/dev", "devtmpfs");
> + if (ret)
> + exit_failure("mount /dev", ret);
> + }
> +
> + ret = execve(argv[0], argv, envp);
> + if (ret)
> + exit_failure("execve", ret);
> +
> + return 0;
> +}
> diff --git a/lib/kunit/uapi.c b/lib/kunit/uapi.c
> index
> 121146dda533b3f90aca37c20bd0e7a1d20cb3b5..bccc081a6538507724c1ef340203cfd147170dc4
> 100644
> --- a/lib/kunit/uapi.c
> +++ b/lib/kunit/uapi.c
> @@ -139,7 +139,7 @@ static int kunit_uapi_user_mode_thread_init(void *data)
> kernel_sigaction(SIGABRT, SIG_DFL);
>
> complete(&ctx->setup_done);
> - ctx->exec_err = kernel_execve(ctx->executable, argv, NULL);
> + ctx->exec_err =
> kernel_execve(kbasename(BLOB(kunit_uapi_preinit)->path), argv, NULL);
> if (!ctx->exec_err)
> return 0;
> do_exit(0);
> @@ -239,6 +239,7 @@ static int kunit_uapi_run_executable_in_mount(struct
> kunit *test, const char *ex
>
> static int kunit_uapi_run_executable(struct kunit *test, const struct blob
> *executable)
> {
> + const struct blob *preinit = BLOB(kunit_uapi_preinit);
> const char *exe_name = kbasename(executable->path);
> struct vfsmount *mnt;
> int err;
> @@ -247,7 +248,13 @@ static int kunit_uapi_run_executable(struct kunit *test,
> const struct blob *exec
> if (IS_ERR(mnt))
> return PTR_ERR(mnt);
>
> - err = kunit_uapi_write_file(mnt, exe_name, 0755, executable->data,
> blob_size(executable));
> + err = kunit_uapi_write_file(mnt, kbasename(preinit->path), 0755,
> + preinit->data,
> + blob_size(preinit));
> +
> + if (!err)
> + err = kunit_uapi_write_file(mnt, exe_name, 0755,
> + executable->data,
> blob_size(executable));
>
> if (!err)
> err = kunit_uapi_run_executable_in_mount(test, exe_name, mnt);
>
> --
> 2.49.0
>
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